The present invention relates generally to tissue sampling devices and relates more particularly to transbronchial needle aspiration devices.
In order to diagnose and to stage lung cancer in a patient, it is often necessary to biopsy a tissue sample from a nearby lymph node of the patient. One type of technique that has been used in the past to obtain such a tissue sample involves percutaneously inserting a sampling needle through the patient's chest into the patient's lung and then through the bronchial wall of the lung into a nearby lymph node. Examples of devices adapted for percutaneous tissue sampling are disclosed in the following U.S. patents, all of which are incorporated herein by reference: U.S. Pat. No. 5,971,939, inventors DeSantis et al., which issued Oct. 26, 1999; U.S. Pat. No. 5,713,368, inventor Leigh, which issued Feb. 3, 1998; U.S. Pat. No. 4,799,494, inventor Wang, which issued Jan. 24, 1989; and U.S. Pat. No. 4,766,907, inventors de Groot et al., which issued Aug. 30, 1988.
Although the above-described percutaneous sampling technique has proven satisfactory in terms of time and expense, such a technique does have its shortcomings. One such shortcoming is the risk of uncontrollable bleeding if the biopsy needle, which may be quite large in diameter, pierces or shears a blood vessel. Another shortcoming is the risk of pneumothorax, i.e., lung collapse, resulting from the puncturing of the lung by the biopsy needle, causing air to leak from the lung and to accumulate between the lung surface and the chest cage. In fact, if pneumothorax is severe enough, the patient may require a chest tube to drain air from the chest cavity. Moreover, in extreme cases, the condition may be fatal. Still another shortcoming is the risk of infection resulting from the percutaneous insertion of the needle into the patient.
Accordingly, another technique that has been used to obtain a lymph node tissue sample is transbronchial needle aspiration (sometimes referred to as “TBNA”). In transbronchial needle aspiration, the distal end of a bronchoscope is inserted through a patient's mouth and to a neutral location within the patient's lung, the proximal end of the bronchoscope not being inserted into the patient and, instead, extending externally thereto. The distal end of a TBNA device is then inserted through a working channel of the bronchoscope, the proximal end of the TBNA device not being inserted into the bronchoscope and, instead, extending externally to the patient. The TBNA device typically comprises a catheter, a wire longitudinally disposed within the catheter, a histology sampling needle coupled to the distal end of the wire, a cap coupled to the proximal end of the wire and accessible externally to the patient for moving the wire relative to the catheter so as to alternately extend the needle beyond the distal end of the catheter and retract the needle into the catheter, and a port accessible externally to the patient for coupling a syringe to the proximal end of the catheter so that the syringe may provide suction to the catheter.
The TBNA device is typically loaded into a bronchoscope with its needle in a retracted position and with a syringe attached to the port. Once confirmation is received that the distal end of the TBNA device has passed entirely through the bronchoscope (such confirmation typically being provided using a video channel of the same bronchoscope), the bronchoscope and the TBNA device are advanced together to the target site, and the needle is advanced to its extended position. The needle is then inserted through the bronchial wall of the patient and into a nearby lymph node. At this time, the syringe is used to apply suction. In the unfortunate event that the needle errantly penetrates a blood vessel, instead of a lymph node, the application of suction causes blood to be aspirated into the catheter and the syringe, where it is detected. In such a case, the application of suction is discontinued and the bloodied TBNA device is removed from the bronchoscope and the patient. A fresh TBNA device is then loaded into the bronchoscope and the patient in the manner described above, and another attempt is made to penetrate the lymph node.
It while suction is applied, it appears that the sampling needle has penetrated a lymph node, as is desired, the catheter is agitated to help shear tissue from the penetrated lymph node into the sampling needle. With a tissue sample thus disposed within the sampling needle, the needle is retracted into the catheter. The TBNA device is then removed from the bronchoscope and the patient. The needle is then advanced out of the catheter, and negative suction is then used to expel the tissue from the sampling needle onto a slide or the like for histological examination.
Examples of TBNA devices are disclosed in the following patents, all of which are incorporated herein by reference: U.S. Pat. No. 5,056,529, inventor de Groot, which issued Oct. 15, 1991; U.S. Pat. No. 4,966,162, inventor Wang, which issued Oct. 30, 1990; U.S. Pat. No. 4,890,626, inventor Wang, which issued Jan. 2, 1990; U.S. Pat. No. 4,791,937, inventor Wang, which issued Dec. 20, 1988; U.S. Pat. No. 4,766,906, inventor Wang, which issued Aug. 30, 1988; U.S. Pat. No. 4,702,260, inventor Wang, which issued Oct. 27, 1987 U.S. Pat. No. 4,693,257, inventor Markham, which issued Sep. 15, 1987; U.S. Pat. No. 4,617,940, inventor Wang, which issued Oct. 21, 1986; U.S. Pat. No. 4,532,935, inventor Wang, which issued Aug. 6, 1985; and U.S. Pat. No. 4,249,541, inventor Pratt, which issued Feb. 10, 1981.
Referring now to FIGS. 1 and 2, there are shown perspective and enlarged fragmentary section views, respectively, of a conventional, commercially available embodiment of a TBNA device, said TBNA device being represented generally by reference numeral 11.
Device 11 comprises a handle or body 13. Body 13 is a branched or T-shaped, tubular member shaped to include a first port 15 at its proximal end, a second port 17 at its distal end, and a third port 19 extending perpendicularly to and between said first port 15 and said second port 17. Each of first port 15, second port 17 and third port 19 is in fluid communication with the other two ports. Third port 19 is adapted to receive a syringe for use in providing suction to device 11.
Device 11 also comprises a flexible catheter 21. Catheter 21 has a proximal end and a distal end 23, the proximal end of catheter 21 being fixedly mounted within second port 17.
Device 11 additionally comprises a metal hub or tip 25. Tip 25 is a generally tubular member having a proximal end 27 and a distal end 29. A plurality of external barbs 31 are formed on tip 25 intermediate to proximal end 27 and distal end 29. Proximal end 27 and barbs 31 are mounted within catheter 21 proximate to distal end 23, with distal end 29 of tip 25 not being inserted into catheter 21, but rather, externally abutting distal end 23 of catheter 21.
Device 11 further comprises a flexible wire 35, wire 35 having a proximal end 37 and a distal end 39. Proximal end 37 of wire 35 is fixed to a cap 41, cap 41 being adapted to be screwed onto first port 15 of body 13. The remainder of wire 35 is threaded through ports 15 and 17 of body 13 and into catheter 21, with distal end 39 of wire 35 being disposed within catheter 21 proximate to distal end 23. A stop (not shown) is provided on wire 35, said stop being engageable with body 13 to delimit proximal movement of wire 35.
Device 11 also comprises a histology sampling needle 51, needle 51 having a proximal end 53 and a distal end 55. Proximal end 53 of needle 51 is fixed to distal end 39 of wire 35. Distal end 55 of needle 51 is shaped to include a sharp tip. A bore 57 extends proximally from distal end 55 of needle 51 to a side opening 59 proximate to proximal end 53. An annular seal 61 is mounted over needle 51 just distal to side opening 59, seal 61 being adapted to abut proximal end 27.
Device 11 may be used essentially in the fashion described above to obtain a tissue sample. To place needle 51 in its advanced position, i.e., so that distal end 55 of needle 51 extends beyond tip 25, one moves cap 41 distally and screws cap 41 onto port 15. Conversely, to withdraw or to retract needle, i.e., so that distal end 53 of needle 51 is disposed within tip 25, one unscrews cap 41 from port 15 and moves cap 41 proximally relative to body 13 until restrained by the aforementioned stop.
Although device 11 is satisfactory in many respects, the present inventors have identified certain shortcomings therewith. One such shortcoming is that, whereas device 11 includes means for retaining needle 51 in its extended position (namely, by screwing cap 41 onto port 15), device 11 does not include corresponding means for retaining needle 51 in a retracted position. Consequently, if one wishes to ensure that needle 51 is not advanced through distal end 23 of catheter 21 at an inopportune moment, one must constantly pull cap 41 proximally relative to body 13. However, as can readily be appreciated, such a requirement substantially complicates the manipulation of device 11, especially by an individual operator.
Another shortcoming identified by the present inventors with device 11 is the branched shape of body 13 and the resultant orientation of a syringe coupled thereto through port 19. More specifically, the present inventors have found that the perpendicular orientation of a syringe relative to the longitudinal axis of catheter 21 makes device 11 cumbersome and difficult to manipulate by an individual operator.
Yet another shortcoming identified by the present inventors with device 11 is that, when needle 51 is in its extended position and a load force is applied to the distal end 53 of needle 51 (such as is the case when needle 51 is used to penetrate a tissue), needle 51 tends to be moved proximally relative to catheter 21, thereby effectively shortening the usable length of needle 51 for penetrating the tissue. Such a loss in the usable length of needle 51 occurs because wire 35 has an outer diameter that is considerably smaller than the inner diameter of catheter 21, giving wire 35 room to move laterally within catheter 21. Consequently, when catheter 21 is bent, as is the case when device 11 is deployed in a patient, and a load force is applied to needle 51, wire 35 tends to take the longest possible path through catheter 21.
Conversely, when cap 41 is pulled back relative to catheter 21 to its fully retracted position and catheter 21 is bent to a substantial degree, needle 51 may not fully retract relative to catheter 21. This is because of the aforementioned difference between the outer diameter of wire 35 and the inner diameter of catheter 21 and the tendency of wire 35 to take the shortest possible path through catheter 21. As can readily be appreciated, if needle 51 cannot be fully retracted when sampling is not being performed, damage may occur to equipment, operators and/or the patient.
Still another shortcoming identified by the present inventors with device 11 is that tip 25 is susceptible to becoming dislodged distally from catheter 21. As can readily be appreciated, if tip 25 were to become separated from catheter 21, the risks to the patient would be considerable. Such a susceptibility of tip 25 to becoming dislodged is due, in part, to the fact that tip 25 is held within catheter 21 only by the friction-fit of catheter 21 over barbs 31 and proximal end 27. This susceptibility is exacerbated by the fact that, when needle 51 is advanced to its extended position, seal 61 applies a distally directed force against tip 25. In addition, because catheter 21 has a tendency to bulge radially outwardly in the area where it overlies barbs 31, this bulged area of catheter 21 is susceptible to becoming snagged on the distal end of a bronchoscope when device 11 is retracted into the bronchoscope. Such snagging results in additional distally directed force being applied to tip 25 relative to catheter 21.
Still yet another shortcoming identified by the present inventors with device 11 is that distal end 29 of tip 25, which is not disposed within catheter 21, but rather, lies externally thereto, has a tendency to scratch and, thus, to damage the working channel of a bronchoscope.
Still a further shortcoming identified by the present inventors with device 11 is that, when needle 51 is retracted, distal end 55 of needle 51 has a tendency to be withdrawn proximally from hub 25. This requires needle 51 to be re-aligned properly with hub 25 in order for needle 51 to be re-inserted into hub 25.
Still yet a further shortcoming identified by the present inventors with device 11 is that seal 61 often does not create an air-tight seal against tip 25 when needle 51 is placed in its fully extended position; as a result, the full extent of the vacuum force applied to bore 57 of needle 51 by the syringe is frequently not experienced.